It is already known to use sensors to detect low rotation rates, on the order of a few degrees per second, for example in measuring the rotation rate of a motor vehicle about its vertical yaw axis, for control of travel dynamics or for navigation purposes. In such known sensors, a tuning fork structure, oriented parallel to the rotation axis, is stimulated or excited to oscillate in a plane perpendicular to the rotation axis. Such sensors must take into account the so-called "Coriolis" force caused by rotation of the earth. In case of rotation about the rotation axis, Coriolis forces are exerted on the oscillating tuning fork tines perpendicular to the rotation axis and perpendicular to the direction of excitation, i.e. to the deflection of the tines in the absence of a rotary motion. One can detect and evaluate the rotation rate by adjusting for the Coriolis-force-induced deflection of the tines perpendicular to the direction of excitation.
German Patent Application P 40 22 495.3 (Bosch docket R. 23632), filed July 1990, and corresponding U.S. Ser. No. 07/988,966.SEIPLER+, describes various embodiments of a rotation rate sensor having a sensor element structured from a monocrystalline silicon wafer and at least one oscillating body, preferably a pair of them, connected over one or more rods to a fixed frame. The oscillating bodies are capable of oscillating in two respectively perpendicular directions. The application describes various excitation possibilities of the oscillating body in a first oscillation direction lying in the wafer plane, for example electromagnetic excitation, thermomechanical excitation, and various possibilities for electrostatic excitation. This rotation rate sensor is equipped with means for detection of deflections of the oscillating body in the second oscillation direction.
The article "Laterally Driven Polysilicon Resonant Microstructures" by William C. Tang, Tu-Cuong H. Nguygen and Roger T. Howe in Sensor and Actuators, 20 (1989) 25-32 describes various polysilicon structures which can be oscillated and supported on carriers, and describes methods for their manufacture.